Tarnish-preventive composition comprising hydroxy-containing thiol sulfides

ABSTRACT

A tarnish-preventive composition for silver and copper surfaces comprising: A. HYDROXY-SUBSTITUTED MERCAPTO SULFIDES HAVING THE FORMULA   B. An abrasive, and C. THE BALANCE A DILUENT.

States Werner et a1.

stem

[54] TARNlSH-PREVENTIVE COMPOSITION COMPRISING HYDROXY-CONTAINING THIOLSULFIDES [72] inventors: Paul F. Warner, Phillips; Edward E.

Huxley, Borger, both of Tex.

[73] Assignee: Phillips Petroleum Company [22] Filed: Sept. 1, 1970 [21]Appl. No.: 68,759

Related US. Application Data [62] Division of Ser. No. 751,060, Aug. 8,1968, Pat. No.

[52] US. Cl. ..106/3,106/14,117/127, 148/624, 252/161, 252/395 [51] Int.Cl. ..C08h C09d C09q [58] Field ofSearch ..106/3-10, 14, 287 S; 260/609;117/127; 148/624; 252/161, 395

[56] References Cited UNITED STATES PATENTS 3,567,782 3/1971 Wameretal...260/609 Feb. 8, 1972 OTHER PUBLICATIONS Culvenor et aL: J, Chem. Soc.(1949). pp. 278-282. Owen et al.: Chem. Abstracts, Vol. 46. p. 9058(1952).

Primary ExdminerJoan B. Evans Attorney-Young and Quigg ABSTRACT O b. Anabrasive, and

c. the balance a diluent.

2 Claims, No Drawings RELATED INVENTIONS This application is adivisional application of our copending application having Ser. No.751,060, filed Aug. 8, 1968 now US. Pat. No. 3,567,782.

BACKGROUND OF THE INVENTION This invention relates to a heavy mercaptancompound. In another aspect, this invention relates to ahydroxy-substituted mercapto sulfide which is effective as a tarnishinhibitor. In accordance with a further aspect, this invention relatesto a hydroxy-substituted mercapto sulfide useful as tarnish inhibitorfor silver, copper, and other tamishable metals. In accordance withanother aspect, this invention relates to a method for producinghydroxy-substituted mercapto sulfides by the reaction of a dimercaptanwith a long chain epoxide.

Tarnishable metals such as silver and copper are well known to tarnishrapidly in normal atmospheres. A housewife who owns silverware, a silverservice, or copper utensils, finds it necessary to polish these utensilsfrequently in order to maintain their attractive appearance.

A number of antitamish agents have been suggested to prevent the tarnishof silver or copper. IN general, these compounds attach to the metal,forming a thin invisible film which prevents the attack of sulfur oroxygen on the metal. While the antitamish agents of the prior art can beused alone, it is generally preferred, for household use, to incorporatesuch agents into a paste or liquid composition. Such a polishingcompound will remove old tarnish through incorporation of a lightabrasive agent, and it will simultaneously treat the clean surface withthe antitamish agent to prevent future tarnish.

Accordingly, an object of this invention is to provide effective tarnishinhibiting agents for silver, copper and other metals.

It is another object of this invention to provide an improved antitamishagent and polish composition containing the-same.

A further object of this invention is to provide an improved process forthe production of hydroxy-substituted mercapto sulfides.

Other aspects, objects, as well as the several advantages of thisinvention will be apparent to those skilled in the art upon reading thedisclosure and appended claims.

SUMMARY OF THE INVENTION The novel compounds of the invention have thegeneral formula represented by HSRSOH;CHR',

wherein R is an alkylene group having one to five carbon atoms,inclusive, and R is a saturated aliphatic radical having from to 20carbon atoms, inclusive.

Further, according to the invention, tamish-preventive compositions areprovided comprising a hydroxy-substituted mercapto sulfide having thegeneral formula defined above, an abrasive, and the balance a diluentand optionally an odorizer and/or a suspending agent.

The compounds falling within this generic formula. have very little odorand display good tarnish inhibition when applied to tarnishable metalssuch as silver and copper.

The novel compounds of the invention are conveniently prepared by theinterreaction of a long chain epoxide having 12 to 22 carbon atoms witha dimercaptan having the formula HSRSI-I wherein R is an alkylene groupcontaining one to five carbon atoms in the presence of a catalyst. Apresently preferred catalyst is an alkali metal hydroxide in analcoholic solution. More preferably, sodium hydroxide is employed as acatalyst.

DESCRIPTION OF PREFERRED EMBODIMENT I-Iydroxy-substituted mercaptosulfide compounds produced according to the invention falling within thescope of the generic formula set forth above include:

mercaptomethyl 2-hydroxypentadecyl sulfide Z-mercaptoethyl2-hydroxyhexadecyl sulfide 3-mercaptoethyl 2-hydroxyheptadecyl sulfide4-mercaptobutyl Lhydroxyoctadecyl sulfide S-mercaptoamyI2-hydroxyoctadecyl sulfide Z-mercaptoethyl-2-hydroxyoctadecyl sulfide2-mercaptoethyl 2-hydroxydocosyl sulfide I The currently most preferredcompounds falling within the group above include'the hydroxy-substitutedmercapto sulfides produced by the reaction of 1,2-ethanedithiol with astraight chain epoxide containing 12 to 22 carbon atoms. This producthas been found to be a superior tarnish inhibitor for silver.

Other dimercaptans that can be employed include 1,3- propanedithiol,1,4-butanedithiol, and 1,5-pentanedithiol. If desired, mixtures of thedimercaptans can be employed when desired.

Representative examples of suitable epoxides that can be employedinclude pentadecylene oxide, hexadecylene oxide, heptadecylene oxide,octadecylene oxide, or mixtures of these. The These relative amounts ofreactants which are to be employed with be dictated by the type ofproduct which is desired. Generally, the mole ratio of dimercaptan toepoxide is broadly 20:1 to l:l,and preferably 5:1 to 15:1.

In carrying out the method of the invention, the epoxide and dimercaptanare ordinarily contacted at a reaction temperature of 75 to 300 F.,preferably 175 to 225 F. and for a period of time from 30 minutes to 5hours.

Acids or bases may be used as catalysts for this reaction. A catalyst,for example, sodium hydroxide, is employed in catalytic amounts of fromabout 0.05 to 2 percent by weight, based on the amount-of epoxidecharged to the reaction. Sodium methylate, sodium ethylate, or otherbasic materials, such as amines, may be used. After the reaction iscomplete the product can be recovered by any conventional means, such asby vacuum or fractional distillation from the reaction mixture.

The compounds of the invention find utility in the many known areaswhere mercaptans are usable, and particularly where the normal. odorassociated with mercaptan compounds is objectionable. Because of thevery low odor of the compounds of this invention, they can be used inconjunction with paint, sealing compounds, silver polish compositions,and so forth. The compounds find particular utility in making of silverand copper polish compositions. These compounds not only have a very lowodor necessary for successful polish compositions, but have excellenttamish-inhibiting properties. For such an application the compoundswould normally be mixed with a light abrasive agent such as chalk,silica alumina, a diluent such as water, or a lower alcohol and asuspending agent. Perfumes may be added if desired.

Whilethe compounds may be directly applied to previously cleaned metal,in the preferred embodiment the antitamish agent will be compounded intoa polishing composition. Abrasive powdersthat can be included oremployed, such as chalk, silica, or alumina, are known in the prior artas illustrated in US. Pat. No. 2,205,l 15.

The satisfactory polishing composition will also include a diluent. Theamount of diluent will depend upon the consistency of the polishingcompound desired. Generally I to weight percent of polar solvent can beused as a diluent, with water or a lower alcohol being preferred.

In order to prevent the abrasive powder from settling out of suspension,a small quantity of a suspending agent should be employed. Such agentsare well known to thoseskilled in the Forexample, a silver polishcomposition can be compounded withthe following general ranges: 1 to 50weight percent of a hydroxy-substituted mercapto sulfide of theinvention, 5 to 98 weight percent abrasive, to weight percent odorizer,and 0 to 1 weight per cent suspending agent. sufficient diluent, e.g.,l-90 weight percent, is then added to form a composition of the desiredconsistency.

EXAMPLE I The antitamish agent 2-mercaptoethyl-2'-hydroxypentadecylsulfide was prepared by the reaction of 1,2- ethanedithiol with asaturated straight chain C, -C,,, hydrocarbon with a terminal epoxygroup using alcoholic sodium hydroxide as the catalyst. Thehydroxy-substituted mercapto sulfide produced gave a top crude yield of67 mole percent with about 50 weight percent mercaptan purity. A portionof the crude was purified by taking it overhead in a Brush still. Theoverhead product represented a 58 mol percent yield and had a mercaptanpurity of about 97 percent.

The equipment used included a three-necked flask equipped with a refluxcondenser, dropping funnel and a variable speed stirrer. The reactiontemperature was controlled by means of a heating mantle and Variac.

The mercaptan was prepared in the following manner: the1,2-ethanedithiol (4.4 moles) containing 2 weight percent of a saturatedsolution of sodium hydroxide in ethanol as catalyst was placed in thereactor. The reactor was heated to 200 F.

- The epoxide was added dropwise to the reactor over a period of 105minutes. The temperature was maintained between l95and 220 F. during theaddition. After all of the epoxide was added, the reactor was held at2l5to 220 F. for an additional 4 hours to allow the reaction to go tocompletion. The catalyst was not removed from the reaction product.

The reaction product was vacuum flashed at 1 millimeter of mercury and325 F. A portion of the kettle product from this flash operation wasretained for evaluation as a silver tarnish inhibitor.

The remainder of the topped crude was charged to the Brush still. About66 weight percent of the charge was taken overhead at 65 to 4 micronspressure and a kettle temperature of 290to 450 F. Approximately 85weight percent of the overhead material had a mercaptan sulfur contentof 9.7 weight percent or a mercaptan purity of 97 weight percent(theoretical mercaptan sulfur is 9.95 weight percent).

Properties of the epoxide feed and the crude purified mercaptan productmade from it are listed in Table I.

TABLE 1 Properties of Feedstock and Products from Synthesis of HighMolecular Weight l-Thiol from Nedox i518 and 1,2-

l. Nedox [S l 8 is a straight saturated chain with a terminal epoxygroup, with C to C chain length, sold by ADM Chemicals.

2. Weight percent by chromatograph.

The material balance data for the topped crude and purified mercaptanmade from the oxide are given in Table ll.

TABLE ll Material Balance Data for High Molecular Weight l-Thiol fromNedox 1518 and 1,2-Ethanedithiol Kettle Product 189 Yield, Pounds ofSOweight percent material as kettle product from flash distillation perpound of Nedox was l.l9.

Yield, Pounds of 97 weight percent product as overhead fraction fromBrush still per pound of Nedox was 0.79.

l. Nedox l5 1 8 is a straight saturated chain with a ten'ninal epoxygroup, with C, to C chain length, sold by ADM Chemicals.

2. Based on Nedox 15 l 8 and 100 percent recovery.

3. Assumed to be l,2-ethanedithiol.

4. About 50 percent mercaptan by mercaptan sulfur.

EXAMPLE II The 2-mercaptoethyl-2'-hydroxy C C sulfide product producedaccording to Example l exhibited excellent antitarnish inhibitioncharacteristics. A formulation was made of the inhibitor of theinvention, as well as known tarnish inhibitors using a water suspensionof the tarnish inhibitor and a polishing grit. These polishes were madeas follows:

4.19 percent or 1.4 grams tarnish inhibitor to be evaluated 5.98 percentor 2.0 grams liquid Ivory detergent 14.97 percent or 5.0 grams Bon Amipolishing grit 74.85 percent or 25.0 grams of water.

Silver test strips were cleaned with the polishes formed as noted aboveand were suspended in a desiccator containing a controlled hydrogensulfide atmosphere of 200-300 p.p.m. by volume by adding 1 ml. of a 1weight percent sodium hydrosulfide water solution to 100 ml. of water ina desiccator. The tarnish inhibitors tested exhibited varying degrees oftarnish inhibition.

After about 24 hours exposure, the silver strip had a light tarnish forthe specimen treated with the 2-mercaptoethyl-2'- hydroxy C -C sulfideproduced according to Example 1. Specimens treated with known prior artinhibitors had a heavy tarnish after about the same length of exposure.In fact, some of the prior art inhibitors were heavily tarnished afteronly about 8 hours exposure.

EXAMPLE n In another test using percent solution of an inhibitor intoluene and applied to silver strips which had been polished with BonAmi, washed and dried before application of the toluene solution, it wasagain found that the inhibitor of the invention produced according toExample 1 was only lightly tarnished after over 20 hours exposure to H8.

in one test, silver was cleaned with Ben Ami and coated with 10 percentsolution of the inhibitor and then exposed to 1 ml. of 1 percent sodiumhydrosulfide solution in 100 mL water.

The inhibitor of the invention exhibited a higher rating as a tarnishinhibitor compared to some of the known prior art tarnish inhibitorstested under the same conditions.

We claim:

l. A tarnish preventive composition for silver and copper surfacescomprising a. from about I to about 50 percent by weight of at least onecompound of the formula wherein R is an alkylene group having one tofive carbon 10 atoms and R is a saturated aliphatic hydrocarbon havingfrom 10 to 22 carbon atoms,

b. from about 5 to 98 percent by weight of an abrasive, and c. thebalance a polar solvent.

2. A composition according to claim 1 wherein said compound is2-mercaptoethyl-2-hydroxypentadecyl sulfide.

2. A composition according to claim 1 wherein said compound is2-mercaptoethyl-2''-hydroxypentadecyl sulfide.